Triterpenoids abundantly exist in plant kingdom, wherein the ursolic acid and the derivatives thereof have been reported to have antitumor, anti-inflammatory, antiviral and antioxidant activities.
Reactive oxygen species (ROS) are resulting in oxidation of various cell constituents as DNA, lipid and proteins, and consequently these oxidations may cause damage to the cellular substance leading to cell death as the ultimate consequence. ROS have been implicated in a number of disease including various forms of non-hormone dependent cancers, atherosclerosis, ischemic reperfusion injury, neurodegenerative diseases, chronic inflammatory disease, such as rheumatoid and psoriatic arthritis, and some factors underlying the aging process itself. ROS might also play a role as signaling molecules and as such they may have a role in cell cycle progression.
Several anticancer agents, such as arsenic trioxide, doxorubicin, bleomycin, cisplatin, 5-Fu, and paclitaxel have been shown to induce ROS generation in cancer cells. Various mechanisms have been described, including respiratory chain disruption, redox cycling, or p53-mediated mitochondrial oxidase activation.
Recently, several compound structures and cytotoxic relationships have been reported. However, a series of structures and cytotoxic relationships of ursolic acid derivatives did not appear in literature. Accordingly, there is a need to evaluate the cytotoxicities against tumor cells, the structures and cytotoxic relationships and mechanisms of action of ursolic acid derivatives.